Hey, I'm Nicky Numbers, Professional Poker Player, and I'm going to help you learn when you can bet in Hold 'Em.
The first thing to know about betting is that you can only bet post-flop. There is no bet pre-flop. The blinds are forced bets which means the first aggressive action to enter the pot is a raise.
Post-flop, on the other hand, there are no blinds or forced bets which means that the first aggressive action is a bet. The only time you can bet is on the flop, turn, or river and you're first to act or your opponents have checked to you.
So that's when you can bet, now we're going to talk a little bit about why you should bet.
Reasons to bet include protecting your hand, betting for value because you believe that your hand is stronger than the hands that your opponents are likely to have, or betting as a bluff because you feel that your opponents are likely to fold their hand because it's unlikely that they have a strong made Hold It.
So basically the times to bet are when you like your hand and you're comfortable taking it to Showdown or you think it's likely that your opponents do not like their hands and are going to have difficulty taking Showdown which means when you bet, there's a good chance they'll fold and you'll win an uncontested pot.